Home & Studio Recording - Jan 1985 Making Records

Making Records

Making Records

Making Records

Magazine Archive

Making Records (Part 1)

An intriguing insight into just what is required of the home recordist when setting out to cut your first disc.

Ever thought of making a record or have the technicalities put you off? It's not an easy decision to make but for those who have a go the results can bring enormous satisfaction and, if you are lucky, a little profit as well. So what's involved? Is it really worth consideration or is the whole business best left to others? Record producer Carl Anthony explains what to expect on the road ahead.

Neumann VMS80 cutting lathe.

If there is one thing that concentrates the mind wonderfully, it's putting your hard-earned money at risk. Whether you are a major company or going it alone, that, at the end of the day, is what making records is all about. The bigger the company the larger the overheads, the more records you have to sell. Going it alone won't necessarily turn you into a millionaire but it will provide you with a good basic grounding of how the industry ticks and give you the satisfaction of having achieved something tangible. Even if you don't intend to release your own record it's still useful to know what's going on in the 'backroom'. If you have already decided to have a go then I hope this series of articles goes some way towards avoiding the most common problems.

Making records can be broken down into five main areas: 1) creating the production master 2) disc-cutting 3) metalwork 4) labels and sleeves 5) pressing. Additionally you'll have to sort something out on the distribution side. Rather than discuss the production master, let's look at disc-cutting first. It will become obvious why when you read on.

Disc-Cutting

There is nothing fundamentally difficult in understanding how a disc-cutting lathe works. Before any records can be made you need to create a master disc. This is the job of the disc-cutting equipment and what it does, basically, is translate the electronic signals on tape into a mechanical groove on the master disc. At the heart of this process is the disc-cutting lathe. In many ways the lathe itself resembles a giant-size turntable. It has a motor (usually four speed; 78, 45, 33⅓ and 16rpm), a platter, arm and stylus. The main difference, of course, is that the stylus is designed to cut a groove rather than play one.

Figure 1. The cutting stylus, unlike a playback stylus, is roughly triangular in shape. The above drawing shows the 'back' of the stylus, which cuts the shape of the groove. Note that the actual cutting edges are not sharp but are rounded off (burnished) in order to polish the groove walls.

With a pickup cartridge the side-to-side movement of the stylus following the groove creates an electrical output which is then amplified. In the cutterhead (the disc-cutting equivalent of the cartridge), the incoming electrical signal waggles the stylus which in turn cuts the groove. Seems pretty simple doesn't it? And so it is: that is until you actually start cutting records!

Cutting the master disc is one of the most crucial steps in making a record. Poor quality at this stage means poor quality for the rest of the process. Once the master disc is cut there is no 'fixing it in the mix' from hereon in. And now for the bad news. You won't even get a chance to even hear what you have cut. If you play your master disc even with the best cartridge available you will damage the soft, highly polished walls of the groove. All the subsequent damage will be reproduced on your final pressings and your records will all be secondhand before you have even sold them!

If you are striving for the very best quality then you are going to need good lacquers in order to get good results. The best disc-cutting rooms pay a high price in order to get the best, premium grade lacquers they can find. When you consider the specifications demanded it is not surprising that lacquers are so expensive.

Lacquers - or blanks as they are called sometimes - are aluminium discs coated on both sides with a thin layer of cellulose nitrate lacquer. The coating is only a few thou thick yet has to be perfectly even. If the thickness varies too much then the cutting stylus could hit the aluminium base or not even cut a groove at all. The same goes for the aluminium base. If that is not perfectly flat you'll have the same problems as variable thickness. Any blemish on the mirror-like surface (finger marks, air bubbles, scratches or dust) will all be reproduced on the final records and could cause a motley collection of clicks and pops. There's a high reject rate before lacquers even leave the factory so it's a minor miracle that we have any at all!

Procedure

So now we have our lathe and flat, blemish-free lacquers, what happens next? You decide whether you want to make an album, single, 12 inch or what have you and present your master tape to the disc-cutting engineer. He'll smile, then ask you the first of several awkward questions, "How long is it?" Don't worry if you cannot remember. At fifty pounds an hour he'll be quite happy spending the next 42 minutes and 23 seconds finding out! And if you tell him that it is just the 'A' side of your single, you'll have him rolling around the room in hysterics.

Be realistic when you compile your master tape. Whether it's a single or an album, there is only so much playing time you can usefully use. If we take a look at the actual cutting process you'll see why.

Cutting Process

Although not strictly accurate, imagine the cutting stylus to be 'V' shaped. As it is lowered onto the lacquer so it will start to cut a groove. The deeper the stylus sits, the wider the top of the groove becomes, so the more space it takes up on the surface of the lacquer. Cut at too shallow a depth and your playback stylus will jump out of the groove. Cut too deeply and you will end up digging the stylus into the aluminium base. Find the optimum depth between the two and you have your basic starting point.

The final width of the groove is determined by the width of the stylus and the depth of the groove, but that isn't what gobbles up the space. It is the fact that you have to modulate the groove, or in other words, move it from side-to-side. The further it moves from side-to-side, the more space it takes up. So why not restrict the movement you may ask. You can, very easily. It's called turning the volume down. And when you reach the point were there is no side-to-side movement you will have a silent groove!

In the end like everyone else you'll find yourself having to make a compromise between playing time and recording level. If you end up with a tape that is too long, your disc will be cut at a much lower level than normal. This will mean replay will be more prone to hiss, rumble and surface noise. Couple this with a cheap, noisy lacquer and poor pressings and you can see the sort of problems you will be heading for. That's not the end of the story, unfortunately. Low frequencies also take up a lot of room and create problems in their own right.

Figure 2. The effect various signals have on the shape of the groove.

Frequency Problems

With modern synthesisers, it is all too easy to generate low fundamental bass notes. Although these could be cut onto disc they take up considerable space and when it comes to replaying them, most cartridges would prefer to go into orbit than stay the course. Put all your bass on one channel only and you are really asking for trouble! To get round this last problem simply don't create it in the first place.

High frequencies, you will be glad to hear, don't create any space problems at all. But before you go rushing off to add 15dB at 20kHz just for the sheer hell of it, spare a thought for the cutting engineer. The higher the frequency the faster the cutting stylus has to accelerate. The higher the level,the further it has to travel at this breakneck speed. All this adds up to one thing - blue smoke from the guts of the cutting head and one very crestfallen engineer. With a repair bill, in all probability greater than your own total recording and pressing budget, you are not going to be the most popular guy in town. If in doubt, let the cutting engineer make the final decision about what EQ to use at the top end. He probably has done anyway by inserting a couple of high frequency limiters into the circuit as a matter of course.

Phase Error

So onward we plunge deeper into the secrets of the black art of disc-cutting. Is there any end in sight? Well nearly, but like a good meal, I've saved the best bit till last. Remember when you were wiring up your studio and carefully checking the leads to make sure they were in-phase? Remember the microphone you borrowed, and that new synth? Did you check the phase? Well all is about to be revealed.

If the signal on your tape is out-of-phase, there's little a cutting engineer can do to help you. This is because, normally when the cutting stylus receives a signal it will move from left to right according to what is recorded on each channel. When it receives an out-of-phase signal it moves up and down. And in the case of a severe example, the stylus will lift completely off the lacquer. In some cases it is possible to save the day by 'mono-ing' the bass. As the name suggests, this means making all stereo signals below 500 Hz (typically) into a mono signal. It doesn't always work, however, and the only recourse you'll have is to go away and try again.

So far making records seems like a pretty black picture but don't despair. Cutting engineers can make excellent transfers from tape to disc. It is all a question of using the limitations of the cutting system (and more importantly the final replay stylus) to your benefit rather than trying to fight the laws of physics.

With such techniques as Vari-pitch (variable pitch) an engineer can pack grooves tightly together during the quiet passages of a song then automatically create more space when the signal gets louder. The effect of this is to give you more playing time but even so, if you want your records to have the maximum impact and widest frequency response then I suggest you limit your album sides to a maximum of 22 minutes and singles to four and a half.

Figure 3. When cutting a record it is important to remember that only the one side is done at a time and the whole of one side is done in one operation. You have to start afresh with a new lacquer if any mistakes are made!

In order to handle the master disc, lacquers are typically 1-2 inches larger than the final size of record. Varying the space between the grooves (pitch) creates the various bands between tracks, allows the playback stylus room to find the starting point (run-in groove) and prevents the playback stylus from running into the label (locked groove).

Usually these last two types of grooves are cut at a deeper than normal depth in order to hold the playback stylus more securely in the groove. This is done automatically on most lathes.

Production Master

Now, with a basic idea of disc-cutting behind us, we can set about preparing our production master. A production master is simply a copy of the master tape tailored to meet the needs of the disc-cutting engineer.

Only one side of the lacquer is used when making a master disc so it will save time if you put side A and side B on separate reels of tape. In order to enable the engineer to set up his tape machine to roughly the same azimuth setting as your machine, you'll need to record a 12kHz tone at the front of the tape. You will also need a 1kHz tone for overall level setting and possibly something like 70Hz, 700Hz and 7kHz tones to judge overall frequency response. Don't forget to leave an extra-long piece of leader tape at the start and finish of your tape. Because of the vari-pitch there are two playback heads on a disc-cutting tape machine spaced several feet apart (they run the tape up between the two reels and back again if you are wondering how they do it). So, in order to thread the tape through this extra long tape path, make sure you have at least eight feet of leader tape before your tones begin.

Separate all tracks with leader tape. This will help the engineer to sample different songs quickly. It will also provide the timing between tracks. Usually, this is three to four seconds. For a four second gap at 15ips tape speed you will need five feet of leader (15 inches per second x 4 seconds = 60 inches). At 7½ips you will need half this amount.

You may find that the different tracks on your master tape are recorded at different levels. Now is the time to balance them all up and re-arrange them into the final running order. Any small frequency adjustments can also be made while you are copying the master tape. And that's it!

Box up the two tapes, clearly mark on the box the recording speed, whether it is NAB or IEC equalisation, whether you used Dolby and what test tones you have included. List all the titles and the running times of each of them. Don't forget to include your name and where you can be contacted and hey presto, you're off to a flying start on the first stage of producing your own records.